1995 K2500 350 full performace rebuild

[b454rat]

Machine shop I go to uses diesel oil on initial start. I've had a couple built by him and they turned out fine. Once it's broke it, whatever oil you want to use will be fine.

 

[PlayingWithTBI]

Worded that badly, obviously not a stock tbi but what all did you do to modify your fuel system to support your build?

As far as hardware, I used an EP381 fuel pump, an 18 LB spring in the TB Pressure Regulator, had the TB bored to 46mm and "Ultimate Mods" to it. Then a WBO2 Sensor, and a bunch of tuning.

 

[Supercharged111]

380 hp/400 tq ish would be perfect

Right now I can cruise right up pretty steep hills in 3rd/4th (I have the 5spd as previously mentioned) in the 1000-1200 rpm range (thanks 4.10 gears) and id like to continue to do that. From what I've read as long as I don't go too crazy with my cam I can keep my low end.


Would a zinc additive make a difference? Is there any solution for the oil problem?


Cats aren't an issue, I live in Washington where there's no emissions testing so I won't be running cats.

Worded that badly, obviously not a stock tbi but what all did you do to modify your fuel system to support your build?

Thanks everyone

OK, now I see your cam as listed by you is advertised duration, not at .050". Big difference there, at first it looked like you'd picked a rager of a cam until I looked it up by part number. The problem with flat tappet as I understand it these days isn't so much the oil as it is the inferior Chinese materials being used causing the excessive failures. A cam and valvetrain isn't something I want to risk doing more than once so I'd also be on the train advocating for a Vortec block of yours isn't roller ready. I'm not sure that's enough can for 380hp, but it should make 400+ torque and keep that drivability you described easily. Because of those latter 2 characteristics, I suspect you're not wanting the 380 as much as you think you do. I think the cam size and heads you've chosen will make you happy, but a single plane intake will hurt your power across the board. You're going to need some RPM to take advantage of that. Look for a dual plane idle-5500 as others have stated. I can't speak to Speed master and their quality when it comes to rockers, but I can say my Comp Pro Magnum 1.6 chromoly roller rockers have been dead silent since I put them in in 2016. I went that route as I was paranoid of aluminum, but supposedly the Crane narrow body aluminum units were factory in the LT4 so they're not all junk.

 

[Ekays]

OK, now I see your cam as listed by you is advertised duration, not at .050". Big difference there, at first it looked like you'd picked a rager of a cam until I looked it up by part number.

Flat tappet cam is an automatic no, aluminum rockers also no for durability reasons. You want a dual plane intake for this application, electric waterpump is not needed because you don't need to run the pump in the staging lanes, neither is a special oil pump.

As far as hardware, I used an EP381 fuel pump, an 18 LB spring in the TB Pressure Regulator, had the TB bored to 46mm and "Ultimate Mods" to it. Then a WBO2 Sensor, and a bunch of tuning.

Here's what I'm getting out of all the input, which there is quite a bit of.

My new plan:
Long tube headers (I was gonna go shorties for fitment reasons but I'll find a good set of used truck long tubes)

Dual plane intake

Roller lifter/cam set up

383 stroker

Steel roller rockers

Keep the TBI (as playingwithtbi did)

Get a vortec block

Further questions:

Am I looking at the right sized cams? Supercharged111 kinda explained why the cam I picked might not be the best for my setup. How would I figure out what how my cam will behave based on advertised duration vs .050?

Would stock or lightly ported vortec heads flow well enough for my application if I wanted to save $ on heads? Obviously new valve springs, studs and maybe valves. Could I port them myself?

One more thing. I can get a assembled 383 stroker vortec short block with forged pistons for ~2500. Would this be that much more costly than buying a block and rotating assembly, and paying a machine shop to hone/deck/balance the whole thing? Here's the specs list:

 

[Schurkey]

this will be my first performace rebuild on a 350

I have a 1995 K2500 350... ...Its going to be my daily so it needs to have a fairly flat torque curve. I'd like to make 380 ish hp. I don't tow regularly.

Possible. NOT going to happen with a GM TBI without heaps of trickery.

Even with a different induction system, you'll be playing games with the computer/tuning.

Comp Cams Xtreme Energy Hydraulic flat tappet (#CL12-249-4) cam and lifter kit (Lift: .434" /.444" Duration: 249°/260° RPM Range: 1000-5000)

I don't see that getting 380 hp on a "happy" aftermarket dyno--never mind on a very-rare honest dyno operating the full SAE protocol.

Jegs aluminum heads 195cc intake, 64cc chamber (#555-514063)

OK. Make sure the included valve springs will work with the cam you select. (i.e., are the springs suitable for a roller cam? Will they handle the lift you intend?)

Speedmaster Aluminum Roller Rocker, 1.6 Ratio (#746-PCE261100801)

Oh, HELL, NO. That company sells bottom-feeder Chinese junk. There's nothing in their catalog I'd trust without SUBSTANTIAL inspection, and most of it I wouldn't touch with a ten-foot pole. Their crap is so bad that they had to change the name of the company because folks figured-out that Pro-Comp Electronics sold nothing but dreck. It's easier/cheaper to change the name of the company than to start selling decent product.

ARP bolts and studs kit

Probably overkill. Main studs, and head-bolts would be as far as I'd go. Re-use all the other fasteners so long as they passed a visual examination--not stretched/necked-down, not rusted, not bent, threads in good condition, etc.

Holley sniper II with full fuel system

Read up on all the folks having problems with aftermarket fuel injection systems including Holley-branded.

Single plain intake (tbd)

I guess. I'm told that single-plane manifolds work well with injection; I've historically been a dual-plane guy--but also carbureted.

Rebuild kit from summit (#SUM-SBCKIT3-311)

Absolutely not. You do not know what size main and rod bearings you're going to need, you do not know what size pistons you're going to need, and you REALLY don't want thick, plain cast-iron rings because it's not 1940 any more. Moly-filled top rings were OEM on engines starting in 1965, at least go that far. Ideally, you'd have thin rings and pistons that weren't sabotaged by having low compression height. Those pistons have been reduced by .020 on the compression height, and they use 1970-style enormous thick rings. JUNK.

And you still have to buy a timing set, a cam and lifter set, and the head gasket thickness may or may not be what is best for your combo.

Shorty headers (tbd)

Yeah...maybe.

3in dual exhaust with X pipe and 2 straight through magnaflow mufflers

Not my first choice. "I" would spend actual money for a nice Y-pipe, then a single MANDREL-BENT exhaust of sufficient diameter (3" or bigger) from there--saving the cost of bending one set of pipes, and one muffler.

If you crush-bend the pipes, all bets are off.

Looking at electric water pumps

Oh, HELL NO.

and high output oil pumps aswell (recommendations are appreciated)

M99HV-S from Mellings. Comes with pickup and driveshaft. Will require some trimming of the windage tray, and careful fitment of the pickup assembly. The pickup should work with a stock oil pan, may need something different if you go to a different pan.
www.summitracing.com/parts/mel-m99hvs

Melling M-99HV-S Melling High-Volume Oil Pumps | Summit Racing

Free Shipping - Melling High-Volume Oil Pumps with qualifying orders of $109. Shop Oil Pumps at Summit Racing.

www.summitracing.com

2. Am I going to make the kind of power I want?

I doubt it. RPM too low, cam too mild. Going 383 will help--figure 33 additional cubic inches should be an additional 33-ish horsepower and 40-ish ft/lbs of torque everything else being equal. Perhaps more, depending on the rest of the components selected and the computer tune.

3. Will I make this power reliably

Not with Speedmaster parts, or pistons with specs that were modern forty years ago.

4. Assuming I tear my block down and there is not extreme wear, should I still get it decked and honed?

ABSOLUTELY.
Main saddles align-honed, (recommended with OEM bolts, MANDATORY with ARP Studs) then
Square-decked (at minimum) AFTER the align-hone. Zero-decked would be better. Use a .028--.040 head gasket to achieve reasonable squish/quench.
Bored if needed (likely, but perhaps not), then
Honed as appropriate for the ring package you're using (Moly-faced, I hope.)
Add-in the cost of balancing, ESPECIALLY if you replace the crank. At 5000 rpm, balancing is not absolutely needed IF (big IF) the weight of the new pistons is reasonably close to the previous pistons, and you're using the same crankshaft. But with a new crank...yeah, you're gonna need to balance it.

I'm going for high 300s (380?) So it sounds like a forged bottom end would'nt be extremely necessary. Especially since I don't plan to rev above 5000-5500 rpm.

ALL SBC connecting rods are forged. Either forged mild steel, or forged powdered-metal. At your power level and intended usage, stock rods should be perfectly adequate.

Most SBC cranks are cast iron. INCLUDING the ones falsely-advertised as "cast steel" which is a TOTAL LIE. You could put a forged crank in there, but I don't see the need.

When I was looking at rotating assemblies on summit, I was seeing alot of 383 kits for $600-800. Cast steel and aluminum (not forged). Would it be that much more exspensive to get a 383 kit, have the block machined to a 383, and start with a solid bottom end that way? Would it make sense to go that route for a solid bottom end and spend less on top end? If it's not much more $ than staying with a 350 (because it sounds like i should replace and machine most of the bottom end anyway) I might go that route.

You're going to be screwing with the computer tune anyway. Might as well add some cubes to make it worthwhile.

OTOH, I'd be really careful about the quality of "stroker kit" you buy; because almost all of them are Communist Chinese and some of them are really terrible. NOBODY goes to China to improve quality. They go to China to improve profit margins, and YOU are the one stuck with parts made by slave labor. With Chinese-sourced parts, your only hope of quality is the inspections done here. And that's not going to be from a company advertising low price as a main selling point.

Yes if money allows look at a 383 assembly and no need for forged rods or pistons at 400 Hp

Well, of course the rods will be forged. The crank and pistons might not be, though.

I personally would buy a 350 core engine with the factory roller cam.

Agreed. Then you can drive your truck until the replacement engine is ready to drop-in. No removing the engine and not driving the truck until the machine shop is finished with it three months later.

Machine shop I go to uses diesel oil on initial start.

Used to be that "Diesel" motor oil was dual-rated for both Diesel and Spark ignition. There may still be some that are...but many are now Diesel-ONLY.

COMPLETELY the wrong additive package for our SBCs.

 

[Supercharged111]

I think the mentality used to be that the diesel oil still had the ZDDP? But don't quote me. I thought that while the specific ZDDP had been lowered that something else was upped to replace its function. Not entirely, but to an extent.